1. Field of the Invention
This invention relates to a semi-finished product for the manufacture of a plastic closure of two parts, including a spout element as a first part with a flange fastenable onto a container, and a spout with an outer thread present on its cylindrical spout wall, and a screw cap as a second part, with a cover surface and an inner thread for the closure of the spout.
2. Discussion of Related Art
Two-part plastic closures which include a spout element as a first part and a screw cap as a second part are mass-produced products which are usually attached to soft packaging. Thus, these closures are manufactured in incredibly high numbers. Accordingly, the demands with regard to possible cost savings are enormously high. Costs may be saved, for example, by reducing the number of injection molds, and also by simplifying the assembly method, which thus may be realized in a quicker manner as with simpler assembly machines.
It is obvious to manufacture the two parts of such a plastic closure as a single-part semi-finished product, in order to produce both parts in a single injection mold. Thus, it is possible to proceed from the basic concept of injecting the two parts as one piece positioned over one another in the position correct for assembly, wherein the two parts are connected to one another via breakage bridges. The inner diameter of the two parts arranged over one another, with regard to their inner diameter, must be designed so that the core can be pulled out of the plastic part. In order to permit this, with the previous solutions, the screw cap has been designed such that it includes an outer thread, and the flange element a corresponding inner thread, so that the screw cap has the shape of a peg. The core can extend through the flange element up to the cover surface of the screw cap, and simultaneously the lower edge of the screw cap can be connected to the upper edge of the spout wall via breakage locations. Such solutions are known form various patent documents. European Patent Reference EP-A-502 716 shows such a solution for example.
Plastic closures of this type are hardly accepted on the market. Such solutions may hardly be aesthetically pleasant, and also such closures are not hygienically acceptable. With each pouring activity, the inner thread of the flange element comes into contact with the fluid. If the screw cap is then placed on again and rotated to close, then for example, contrary to what is mistakenly assumed, the thread is not practically scraped in a self-cleaning manner, but rather the material is pressed in the thread flight to the top and to the outside due to certain tribological characteristics when screwing closed. Accordingly, the closure is completely soiled after being used several times. Also, after the opening, one would often want to place the screw cap somewhere, in order with the one hand to hold the receptacle, from which one wishes to pour out, while with the other hand one then holds the receptacle into which to pour out the fluid, or for example with foodstuffs, one holds a spoon or whisk with the other hand. In order to deposit the closure somewhere in the meanwhile, as a result one must place it upside down, wherein the soiled part projects upwards. With reclosure, it is impossible to grip the closure, without contacting the soiled threaded region. This is unpleasant, and also one contaminates the remainder of the foodstuff which is present on the screw thread, and brings this into contact with the contents of the receptacle when closing the closure again. It is because of these considerations that such two-part closures with which the screw cap is screwed into the spout out in a peg-like manner, have not succeeded on the market.
These closures are used on typical drinks containers. The user screws off the screw cap and leads the flange element directly to the mouth. Thus, for hygienic reasons, the spout element is thus protected by the screw cap. A peg-like screw cap may not fulfill this hygienic demand.
It is impossible to manufacture screw caps with inner threads and flange elements with outer threads on the outer wall, as one piece, according to the previous teaching, because the inner diameter of the screw cap is necessarily larger than the outer diameter and most certainly than the inner diameter of the cylindrical spout of the flange element. Accordingly, these two parts may not be manufactured as one piece such that breakage locations are incorporated between the lower edge of the screw cap and the upper edge of the cylindrical spout, and these are manufactured as one piece, because the two-part plastic closure may no longer be removed from the mold.